Posted
by
timothy
on Thursday November 15, 2001 @04:58PM
from the last-words-of-a-star dept.

NaturePhotog writes: "No, it's not CNN bad-mouthing the Empire's latest creation, it's astronomers catching a dying star in the act of becoming a nebula. Radio waves emitted by water molecules helped provide the age of the event."

Actually, it is all probably in vapor form. It's hard to make ices in most of space, since it is rare that molecules come together to make a crystall.

Water will not exist as a liquid in space, basically for the reasons you cite (plus, with effectively zero pressure, the water will just evaporte pretty quickly). But water vapor can exist inside the clouds of other gases, particular atomic hydrogen. Water, being such a great absorber and emitter of radiation, is really easy to spot, so we talk about it a lot.

As the other comment in this thread noted, the water molecules detected are definately in the vapor phase, especially in a planetary nebula of this age (...still very hot). Vaporized water is still water.

Assuming this is a medium mass main sequence star (and it should be to have this behavior at the end of its life) this is the final stage where it is sloughing off its outer atmosphere, and the core of the star (with a mass now less than the Chandresekhar (sp?) limit of 1.4 solar masses) is on its way to degeneracy and whitedwarfdom.

The core should mostly be carbon and helium now - with helium and mostly hydrogen being released in the nebula. The Oxygen is probably remnents from so the of various fusion sequences (like the CNO cycle). The hot elemental oxygen is very likely to encounter a couple of Hydrogen atoms, and next thing you know - boom - you've got water.

As someone else pointed out- the fact that water is such a great absorber of radio energy, and that it only forms early on - it's a great detector.

Water does exist elsewhere in interstellar space, as a cold vapor generally. It probably comes directly from these sorts of events.

Your talking about the bulk properties of water. As the other respondents have pointed out, a water molecule is a water molecule regardless of the bulk state the water is in. What your missing is that unless the water molecules are close enough together to begin with, they won't be able to form ice. So, there is a chance that there won't be any ice crystals even when it gets cold enough in the region.

This was observed using the National Radio Astronomy Observatory's Very Large Array [nrao.edu], which is a (rather cool looking [nrao.edu]) group of 27 radio antennas in New Mexico. The NRAO press release [nrao.edu] on K3-35 contains somewhat more detailed information than the CNN article.